Which indicator on the aft overhead panel indicates a failure in synchronization shaft lock security?

Which indicator on the aft overhead panel indicates a failure in synchronization shaft lock security?

• A. An illuminated amber reverser light
• B. A green REV indication above the N1 RPM readout
• C. A blue ignition light
• D. A white caution light

Answer: (A)

The key idea is that the synchronization shaft lock security has a dedicated fault warning, and it’s shown by an amber reverser light on the aft overhead panel. When the lock that keeps the APU’s shaft aligned with the system can’t be verified as secured, the system flags a fault with this amber reverser indicator. The color and the specific indicator are chosen to alert you to a reversible fault that needs attention, without shutting everything down immediately. The other indicators don’t represent SSL failure: a green REV above the N1 readout signals normal reverser status, a blue ignition light just shows the ignition is on, and a white caution light is a general advisory. So the illuminated amber reverser light is the one that indicates a failure in synchronization shaft lock security.

The key idea is that the synchronization shaft lock security has a dedicated fault warning, and it’s shown by an amber reverser light on the aft overhead panel. When the lock that keeps the APU’s shaft aligned with the system can’t be verified as secured, the system flags a fault with this amber reverser indicator. The color and the specific indicator are chosen to alert you to a reversible fault that needs attention, without shutting everything down immediately. The other indicators don’t represent SSL failure: a green REV above the N1 readout signals normal reverser status, a blue ignition light just shows the ignition is on, and a white caution light is a general advisory. So the illuminated amber reverser light is the one that indicates a failure in synchronization shaft lock security.